"I cried because it was really overwhelming to me that all these really talented people were bringing so much passion and so much talent to the story that I'd written and giving it a new life," explained the author.

The film stars Shailene Woodley as Hazel, a teenager fighting terminal cancer. She meets Gus, played by Ansel Elgort, at a youth cancer support group, and the book and movie follow their romance with the backdrop of their serious health issues.

"The love scene, because to me it's very different than most love scenes in, quote unquote, young adult films," she answered. "It's treated with integrity. I think, oftentimes, our society looks at teenagers and sort of discredits their love or they say, 'Oh, it's cute. It's puppy love. They don't know what real love is.' And you look at adults and you're like, 'Are you actually happy?'"

Her passionate response garnered laughs from the panel and the audience. Elgort said he enjoyed the Amsterdam scenes, calling them the "pay-off."

For his part, Boone revealed that he was initially reserved when it came to casting Woodley as the lead. However, once she read a certain scene, the eulogy, his decision was made.

"When she actually did her audition and did that eulogy scene, the first thing I thought after maybe a minute and a half was, 'Why did I make this so hard on myself?'" Boone laughed.

The other stars were given kudos as well. According to the cast, Wolff is a master improvisor. Woodley gave him credit for improvising the line "I'm blind, but I'm not deaf," playing on Wolff's character Isaac's disability.

Woodley garnered more laughs when asked if it weird playing opposite Elgort as a couple, whereas they played siblings in the recent "Divergent."

"It's not weird because I've always sort of wondered what it'd be like -- kissing my brother," she said, looking at Elgort.

Even with all the laughs, the cast acknowledged the emotional roller coaster that came with working on the film. Dern said having Green there for emotional support made all the difference.

"I have to say, my favorite memory of a movie of walking through the emotional journey of a character would be that we'd have this catharsis or ride each day and most often, at the end of our work, we'd walk away from the camera toward the monitor and there would be John Green with open arms embracing us," she said.

"The Fault in Our Stars" hits theaters June 6. Watch the full press conference below: